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### 13a on practice midterm?

Posted: **Sun Nov 04, 2018 3:34 pm**

by **aisteles1G**

Okay so I use the de broglie equation to get v=1.509*10^-24, then plug that into (1/2)m*v^2 but keep getting 4.44*10^-50. Im using 39.1 as the mass of the potassium ion, what am I doing wrong???

### Re: 13a on practice midterm?

Posted: **Sun Nov 04, 2018 5:50 pm**

by **Jonas Talandis**

39.1 g is approximately the mass of a mole of K ions. You need to divide by avogadro's number to find the actual mass of a single ion. Hope that helps.

### Re: 13a on practice midterm?

Posted: **Sun Nov 04, 2018 6:21 pm**

by **aisteles1G**

Jonas Talandis 1F wrote:39.1 g is approximately the mass of a mole of K ions. You need to divide by avogadro's number to find the actual mass of a single ion. Hope that helps.

I finally got the right answer using this, thank you so much I had spent like an hour stressing and trying to figure out where I went wrong, appreciate it!